Workers combat excavation of dense Triassic rock along the developing Interstate 540 — the outer loop of the Raleigh, NC, beltway — in addition to settlement issues associated with the use of this type of rock as fill.
Lane Construction Corporation began work in April 2004 on two adjoining I-540 projects located in northwest Raleigh that total 5 mi. of new road construction.
According to Ed Craver, resident engineer of the North Carolina Department of Transportation (NCDOT), one project runs from NC 55 to Davis Drive and the second runs from Davis Drive to I-40. The contracted amount for both projects combined is $102 million with approximately 170 Lane employees at the job site daily.
According to Greg Johannes, Lane’s project manager, the rock at this job site is quite hard and can not be dug up with an excavator; therefore Lane leased an 85,000-lb. John Deere 1050 C bulldozer with a single-tooth ripping shank mounted on its back to do the excavation work. In addition, National Drilling and Blasting Co. Inc., of Winston Salem, NC, was contracted to blast approximately 1 million cu. yds. (764,500 cu m) of rock in areas where machines couldn’t be used.
In total, there will be 2.3 million cu. yds. (1.76 million cu m) of unclassified excavation (mostly rock) which will be used as fill on the job site along with 3.6 cu. yds. (2.74 million cu m) of borrow material, consisting of dirt and rock.
The state mandates requirements when using Triassic rock as fill for drainage and paving purposes.
“To obtain the level of compaction needed to ensure that the future roadbed will not shift, the rock is ripped into 1-ft. by 1-ft. pieces,” Johannes said.
Triassic rock is sedimentary and will degrade over time.
“Therefore when used as fill, settlement problems may occur if the material is not handled properly.”
Also, NCDOT specifies that a machine equivalent to an 85,000-lb. Caterpillar D8 is required to compact the soil or rocks so that no void in the fill will occur. The John Deere 1050 C bulldozer fit this requirement.
“Even though this was a big excavation job, it was nothing unusual for Lane; we have the experience to handle the situation,” Johannes said.
Craver said the one thing that has made this job unique is the vast amount of Triassic material.
“It is a very large task,” he said.
Standard road construction will be used at the job site. Bridge construction will involve poured decks with steel and T girder construction.
“This five-mile portion of I-540 will be six lanes, including 12-feet concrete service lanes, and 12-ft. concrete median shoulders, anticipating future use as lanes,” Craver said. “In addition, there will be four interchanges and 21 bridges.”
Approximately 310,000 sq. yds. (260,000 sq m) of concrete will be required for the job.
The total amount asphalt on the job is approximately 140,000 tons (127,000 t), most of which will be placed as a drainage lift under the concrete mainline pavement.
“Lane is directly involved in a high percentage of the work including the excavation, grading, paving and structural bridge work,” Craver stated.
“C.C. Magnum Company of Raleigh, NC, is providing approximately 70 percent of the asphalt work and Rea Contractors of Charlotte, NC, is providing the other 30 percent,” Craver added. “Jones Development of Raleigh, NC, is responsible for the storm drain and utilities, and the NCDOT was responsible for the design of the project.”
Lane also was responsible for erosion and sediment control measures to protect the numerous wetlands and waterways throughout the project, including obtaining the required environmental permits.
“The most challenging aspect of this job,” Johannes stated, “was the overall coordination of a five-mile long job — coordinating all the excavation and bridge work, along with the subcontractors. Because this is all new construction, traffic issues have been minimal. The only areas requiring flagging are where we are widening crossroads.”
Approximately 60 percent of the work for the two projects is complete.
“We are currently working on earthwork, excavation, bridges, asphalt and prepping for concrete paving. We expect the whole project to be complete in August of 2007,” Johannes said.
The I-540 loop will serve northern Wake County and the Raleigh-Durham International Airport and run from the I-40 at the airport past Capital Boulevard for 18 mi. in north Raleigh, carrying around to I-64 near Knightdale in the eastern part of the county.
“Completion of the entire I-540 will provide the commuter traffic around the research triangle a much needed alternative to the current roads — most of which are handling traffic at their capacities already,” Craver said. “However, even when the five miles of I-540 in northwest Raleigh is finished there will still be significant portions of I-540 to complete before the loop is closed.” CEG